Erythrocyte aggregation before and after haemodialysis.
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Adult↗
Biomedical subjects
J F Stoltz
Publications and source records attributed to J F Stoltz.
[Non-newtonian behavior of blood and parietal shear stress in a Poiseuille flow].
The authors study the blood flow in a cylindrical vessel with the consideration of the non-newtonian behaviour of blood. Supposing that the vessel's diameter and the blood velocity at the centre are known (measurable by a Doppler ultrasound velocimeter), we calculate the velocity profiles, flow rate, wall shear stress and shear rate, with 8 non-newtonian models, by a numerical method which allows us to solve the flow system for any non-newtonian fluid. The numerical results are compared with those obtained for a newtonian fluid which remains the most used model in clinical practice. This work shows the importance of the use of a realistic non-newtonian rheological relationship in the estimation of mechanical factors especially the wall shear stress in blood circulation.
Blood Flow Velocity↗
Specific anti-HLA antibody immunoadsorption with columns of fibroblasts or membrane proteins coupled to microcarriers--methodology.
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Adsorption↗
[Rheologic and biophysical aspects of cellular adhesion and aggregation: importance in hemorheology].
Interactions between blood cells in the form of cellular aggregates or adhesion are observed in a variety of normal and pathological conditions. Aggregation of erythrocytes or platelets, adhesion of platelets and leucocytes and immune agglutination of RBC are examples of interactions involving blood cells. Cell adhesion and aggregation are modulated by specific interactions (antigen-antibodies reactions, adhesive macromolecules interactions...) or non-specific (van der Waals forces, electrostatic interactions, molecular bridgings...). These interactions may result in morphological and structural changes, or polarization phenomena. At the dynamic level, cellular adhesion (or aggregation) can divided in 4 main steps: transport, cellular activation (endogenous or exogenous), morphological, physical or steric rearrangements, contact (intercellular or on an artificial surfaces). It will be the nature of the interactions involved in these steps that will determine the binding cohesion and kinetic. In this paper, different types of interactions and the regulation mechanisms of adhesion and aggregation phenomena involved in blood hemodynamics will be summarized and some examples (RBC or platelets aggregation; platelets or leucocytes adhesion) will illustrate the importance of these phenomena in clinical hemorheology.
Biophysical Phenomena↗
Quantitation of factor VIII antibodies by an enzyme-linked immunoassay method.
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Autoantibodies↗
Increased erythrocyte aggregation in insulin-dependent diabetes mellitus and its relationship to plasma factors: a multivariate analysis.
Red blood cell aggregation in vitro (kinetics and shear resistance) was studied in 13 healthy controls and 13 type I (insulin-dependent) diabetic patients free of severe degenerative complications who were matched for age, sex, and body mass index. Measurements were performed with a device that analyzes the laser light backscattered by a blood suspension. Both the velocity of rouleau formation and the cohesion of the rouleau network were significantly increased in diabetic patients. Plasma viscosity and whole-blood viscosity measured at low shear rate (0.95 s-1) were also significantly elevated in the diabetic group. Multivariate analyses of the whole population sample and the diabetic patients confirmed the influence of plasma proteins on the kinetics of aggregation. Fibrinogen levels, which were close to normal, affected mainly the shear resistance of the aggregates. Triglyceride and apolipoprotein (apo) B levels and indexes of metabolic control or protein glycation (fasting blood glucose and fructosamine) also appeared to influence markedly both the kinetics of rouleau formation and the cohesion of the rouleau networks. These rheological abnormalities occurred in diabetic patients before the appearance of any severe degenerative complications. We suggest that these rheological abnormalities are linked to plasma or erythrocyte factors, and are not due to angiopathy.
Adult↗
Hemorheological and hemostatic parameters in children with nephrotic syndrome undergoing steroid therapy.
Disturbances in hemostatic and hemorheological parameters have been investigated in a group of 29 children with nephrotic syndrome: 23 children classified as steroid-sensitive and 6 as steroid-resistant. Studies were performed before prednisone treatment and 3 weeks later, after initiation of steroid therapy. Before treatment, the alterations in hemostatic system involved moderate thrombocytosis with spontaneous aggregation in 19 patients. High levels of fibrinogen, factor VIII, Willebrand factor, protein C, protein S and alpha 2-macroglobulin (alpha 2M) were observed. Factor XII and alpha 1-antitrypsin (alpha 1AT) were lower than normal. Antithrombin III (ATIII) level was normal in the majority of patients. A plasma and blood hyperviscosity syndrome was also observed as well as an increase in erythrocyte aggregation. During treatment, an improvement in the hemostatic parameters was observed in the patients who responded to prednisone. The expected increase in factor VIII (frequently described in the literature) was not observed, while there was a significant increase in protein C. In the steroid-resistant patients, the only significant changes observed were decreased fibrinogen and increased protein C. The hemorheological parameters showed a tendency towards normality regardless of whether or not the treatment provided remission of NS. The relationship between hemorheological and hemostatic factors changes are discussed.
Adolescent↗
Rheologic effects of plasma substitutes used for preoperative hemodilution.
This study was designed to compare the influence of various plasma substitutes, administered for preoperative hemodilution, on blood rheology. We studied 40 patients, ASA grade I, who underwent elective facial reconstructive surgery and received 4% albumin (n = 10), 3.5% dextran 40 (n = 10), gelatin (n = 10), or hydroxyethyl starch (HES) (n = 10). Ten patients, undergoing the same surgical procedure without hemodilution, were chosen as controls. After hemodilution, hematocrit was decreased approximately 30%. Fibrinogen decreased in all tested groups except in the gelatin group. Plasma viscosity decreased with albumin (1.13 +/- 0.05 to 1.06 +/- 0.03 mPa.s; P < 0.01) and increased with HES (1.15 +/- 0.04 to 1.22 +/- 0.05 mPa.s; P < 0.01). At a high shear rate, the blood viscosity decreased in all groups. In contrast, at a low shear rate and at 40% corrected hematocrit, the blood viscosity decreased in the albumin (15.9 +/- 1.9 to 13.1 +/- 2.1 mPa.s; P < 0.01) and the dextran 40 (16.9 +/- 2.9 to 12.8 +/- 2.5 mPa.s; P < 0.01) groups and was unchanged in the gelatin and the HES groups. Erythrocyte aggregation (measured with primary aggregation time) was markedly decreased in the albumin (3.27 +/- 1.74 to 7.03 +/- 2.95 s; P < 0.01) and in the dextran 40 (2.72 +/- 0.58 to 6.24 +/- 2.55 s; P < 0.001) groups, unchanged with HES, and increased with gelatin (2.41 +/- 0.90 to 1.55 +/- 0.33 s). These findings suggest that albumin and dextran 40 may be the plasma substitutes of choice for preoperative hemodilution when this technique aims to improve rheologic conditions.
Adolescent↗
Erythrocyte aggregation--determination of normal values. Influence of age, sex, hormonal state, oestroprogestative treatment, haematological parameters and cigarette smoking.
Erythrocyte aggregation is a physiological phenomenon and constitutes one of the most important factors accounting for the non-Newtonian properties of normal human blood. Pathological aspects have also been described and therapy aimed at reducing hyperaggregability has been proposed. The object of this study was to establish normal values of erythrocyte aggregation parameters as measured by laser light backscattering and to study the influence of various physiological factors. Normal values were determined from a reference population. Sex and age induce variations in erythrocyte aggregation which are neither fibrinogen nor haematocrit dependent and there is a general trend towards stronger aggregation in women, although neither hormonal state nor oestroprogestative treatment appear to influence the female aggregation parameters. In elderly people stronger aggregation is also observed but this effect is of lower magnitude. In vivo, the plasma fibrinogen level is the most important factor influencing erythrocyte aggregation, while variations in haematocrit play a lesser role and mean corpuscular volume, red cell distribution width and white blood cell and platelet counts have no effect. Finally, no difference is noted in cigarette smokers.
Adolescent↗
[Erythrocyte aggregation in patients treated by plasma exchange or plasma administration].
The kinetic (aggregation times) and rheological (dissociation threshold) parameters or erythrocyte aggregation were determined before and immediately after each plasma epuration, using a device based on the analysis of the back scattered light by a blood suspension. We used two techniques of plasma épuration: a) classical plasma exchange: 8 multiple myelomas, 6 Waldenström diseases, with 42 procedures tested; b) plasma treatment/cascade filtration: one Waldenström disease with 9 procedures tested and 37 procedures in one patient suffering from hypercholesterolemia. We have completed this study by checking the rheological parameters in 46 procedures applied in 6 patients with hypercholesterolemia. In these patients, we have used the Kaneka technique (dextran sulfate). The parameters studied were: primary (Ta) and final (Tf) aggregation times, total (gamma D) and partial (gamma S) dissociation parameters. In all cases, the results showed an important decrease of Ta and Tf (with good improvement) and an increase of dissociation parameters showing the efficacy of such therapies. Erythrocyte aggregation constitutes a good panel of parameters to appreciate abnormalities before and after plasma epuration.
Erythrocyte Aggregation↗
[Modifications of hemorheologic parameters in the course of hemodialysis in chronic renal insufficiency].
The influence of haemodialysis (HD) was assessed in 72 patients, undergoing a thrice weekly routine HD for chronic renal failure (CRF). Some of them received human recombinant erythropoietin (Eprex). Measurements were performed before and after the HD session: the erythrocyte aggregation (EA) was carried out by a laser backscattering technique with determination of the aggregation time (AT) and of the dissociation thresholds. Plasma viscosity (PV) was evaluated in an automatic capillary viscometer. Fibrinogen (Fg) levels, haematological features (blood cell count), serum proteins, creatinine, and some other biochemical parameters, were also determined. Anaemia was a common feature. Our results compared to those of a control group, confirmed the erythrocyte hyperaggregation before HD which increased during HD. PV also elevated before HD, further increased after HD; the same finding was observed for Fg. Some of these results might be related to the haemoconcentration. Significant correlations were noted between AT and PV, AT and Fg with closer correlations after HD, suggesting a strong cohesion of RBC aggregates, which enhanced during HD. Correlations were highly significant between relative variations of AT and relative variations of PV, Fg, proteins and body weight, before and after HD. Special attention was given to the group of patients under long term treatment with Eprex compared to non-treated dialysed patients: no significant difference was found between both groups. Our results are in agreement with a blood and plasma viscosity syndrome due to increased EA and with a tendency, to thrombosis reported in those patients.
Adult↗
[Importance of non-Newtonian rheologic properties of blood in erythrocyte transport].
The authors studied the global transport of red blood cells (RBC) in a stationary cylindrical tube flow. The human blood was considered as homogeneous fluid. For geometric and dynamic conditions fixed, the quantity of transported RBC was calculated using different models of constitutive equation: i) Newtonian model with apparent viscosity measured at 128 sec-1; ii) Landel's model for rigidified RBC suspension; iii) three non-Newtonian models (Casson law, power law and a relationship of Sisko). We showed that there was an optimum hematocrit for every model for which the quantity of transported RBC was maximum. The values of optimum hematocrit obtained for the non-Newtonian models varied in function of the tube radius and the pressure drop. It was equally observed that the optimum hematocrit was very small when the red blood cells were rigid. These theoretical results merit experimental studies and open the way to investigations of mechanical transport of RBC (global oxygen transport) under different types of flow conditions.
Biological Transport↗
[Quality control in clinical hemorheology: preliminary study by three centers].
Clinical or pharmacological trials require reproducible laboratory tests. The aim of this work was to investigate the conditions of quality control of two laboratory tests, blood viscosity and red cell aggregation used for hemorheology trials in three centers. The results showed that viscosity measurements require 2 standards. For red cell aggregation, the control suspension standardized media (normal an pathological aggregation) showed a good intercentre reproducibility of the dissociation thresholds but a wide variability of aggregation times. Complementary studies in 5 or 6 centres are planned in order to define national standards of quality control.
Blood Viscosity↗
Increase of hybridoma productivity using an original dialysis culture system.
Hybridoma cell growth and monoclonal antibody production were investigated with a laboratory-made system in which cells were grown in dialysis tubing (MW cut-off 25 kD). The dialysis system contained 10 ml of cell suspension and was immersed in 200 ml of culture medium which when replaced or was at 4-day intervals. With this system, monoclonal antibody concentrations similar to those observed in ascites (concentrations in the order of one gram per liter) were obtained. With no medium replacement, the antibody production was 3.3 g/l and the cell productivity 3.2 x 10(-8) micrograms of IgM produced per cell in one minute. With medium replacement the antibody production was higher, 4.4 g/l but the cell productivity was lower, 1.49 x 10(-8) micrograms per cell in one minute. Cells cultivated in non-optimized conditions were better producers than cells growing in a good environment.
Animals↗
Effects of lisinopril and hydrochlorothiazide on platelet function and blood rheology in essential hypertension: a randomly allocated double-blind study.
AIM: To compare the effects of an angiotensin converting enzyme (ACE) inhibitor and a thiazide diuretic on platelet function and haemorrheological variables, since these factors may contribute to the atherosclerotic and thrombotic complications associated with hypertension. METHODS: Following a 2-week placebo period, 80 male and female patients with mild to moderate hypertension, aged 50 +/- 10 (mean +/- SD) years, were randomly allocated in a double-blind study to 4 weeks of treatment with the ACE inhibitor lisinopril at 20 mg once a day or the diuretic hydrochlorothiazide at 25 mg once a day. Venous blood was sampled before and at the end of the 4-week treatment period to assess platelet function and haemorrheological variables. RESULTS: Both treatments lowered systolic and diastolic blood pressure equally and had no significant effect on platelet counts and platelet aggregation in response to ADP and to arachidonic acid. Haematocrit plasma viscosity and blood filterability were not altered by either drug. Hydrochlorothiazide tended to increase and lisinopril tended to decrease whole blood viscosity at all shear rates but these changes did not reach statistical significance. Lisinopril increased the erythrocyte aggregation time (from 1.98 +/- 0.50 to 2.08 +/- 0.52 s) and decreased the disaggregation shear rate (from 159 +/- 46 to 153 +/- 40 s-1) and the disaggregation shear stress (from 705 +/- 257 to 659 +/- 204 mPa). Hydrochlorothiazide induced the opposite effects (2.00 +/- 0.47 to 1.92 +/- 0.39 s, 181 +/- 531 to 196 +/- 82 s-1 and 813 +/- 268 to 868 +/- 392 mPa, respectively) with a statistically significant (P < 0.05) intergroup difference. CONCLUSIONS: These findings suggest that chronic treatment with the ACE inhibitor lisinopril, but not the diuretic hydrochlorothiazide, may produce favourable effects on blood rheology, but the clinical relevance requires further investigation.
Adult↗
[In vivo effects of plasma substitutes on the rheologic properties of blood].
The objective was to investigate in vivo the rheological effects of plasma substitutes (fluid gelatin, dextran 40, dextran 60, hydroxyethylstarch). The study was performed during a hypervolemic hemodilution in 60 adult volunteers who underwent an odontological surgery. Two control groups were infused with Ringer-Lactate or 4% human albumin. Each patient was infused with 500 ml of plasma substitute or control fluid. Blood samples were obtained at four different times: prior to (t0) and immediately after (t1) the infusion, then 3 hours (t2) and 24 hours (t3) after the hemodilution. At t1 and t2, plasma viscosity did not present important variations, except for the group infused with dextran 60 where a significant increase in plasma viscosity was observed. Blood viscosity and erythrocyte aggregation measurements were performed at hematocrit 40% to determine the intrinsic properties of substitute and eliminate the effects of hemodilution. Blood viscosity at high shear rates underwent minor variations in all groups. In contrast, blood viscosity at low shear rate and aggregation parameters exhibited important variations which markedly depended on the used substitute. The infusion of Ringer-Lactate, albumin and dextran 40 induced a significant decrease in blood viscosity and in erythrocyte aggregation. With dextran 60 and gelatin, blood viscosity and erythrocyte aggregation increased. Finally, the infusion with hydroxyethylstarch did not present important differences as compared to the results recorded at t0. Twenty for hours after the infusion, it should be noted an increase in plasma fibrinogen, probably due to surgery, which caused an increase in erythrocyte aggregation in all groups.(ABSTRACT TRUNCATED AT 250 WORDS)
Adolescent↗
[Validation of the virus inactivation capacity of a procedure of human plasma albumin purification by chromatography].
Almost the whole of the human plasma albumin preparations intended for clinical or biological uses is at present fractionated by cold ethanol precipitation technics based on the Cohn method. However, ion-exchange chromatographic processes have been recently developed. The aim of this work was the evaluation of the viral inactivation efficacy of an automated industrial chromatographic process allowing fractionation of 350 to 400 l of plasma per cycle (one precipitation step, three ion-exchange chromatography steps using the Spherodex-Spherosil gels--Sepracor-IBF, Villeneuve la Garenne, France--and one pasteurization step. Three relevant viruses were selected for this validation study: the hepatitis B virus (HBV), the poliomyelitis virus and the human immunodeficiency virus (HIV). In order to comply with EEC and FDA regulatory documents, significant amounts of the tested viruses were spiked into the different fractions obtained during the various purification steps and their removal or inactivation during the subsequent step were determined. The validation study was performed under conditions which mimic the manufacturing process using fractions obtained during a semi-industrial fractionation. Moreover, residual viral infectivity was checked on after elution and washing of the columns for each chromatographic step. Results have pointed out: a) an overall reduction of 4.4 log 10 for HBV. Infectivity is judged by a combination of several markers and the DNA polymerase activity is the most affected particularly during the three ending purification steps; b) an overall reduction in virus titer > 10 log 10 for the poliomyelitis virus; c) an overall reduction in virus titer > 10 log 10 for HIV (four of the five steps have an important potential to inactivate this virus increasing the safety of the process). Moreover, no residual viral infectivities were detected after washing of the columns. In conclusion, this study showed the viral safety of human albumin purified using the chromatographic Spherodex-Spherosil process. As had been observed for fractionation by means of ethanol, the pasteurization step is necessary to ensure inactivation of two of the three viruses tested (HBV and poliomyelitis virus). This validation study allowed the preparation of a manufacturing and controls document for albumin and a marketing authorization has been issued by the "Laboratoire National de la Santé" (LNS, France).
Chromatography, Ion Exchange↗
[In vitro effects of ionic and non-ionic contrast media on erythrocyte aggregation].
An in vitro model was designed to examine the effect of three contrast media (CM): two non ionic (Iohexol, Iopamidol) and one ionic (Ioxaglate) molecules on erythrocyte aggregation. Red blood cells were suspended in a chemically defined medium (Albumin: 10 g/l), Immunoglobulins: 12 g/l, Fibrinogen: 1.5 g/l) supplemented with various proportions of CM (10-25% V/V). Control samples contained NaCl or Saccharose solutions with a nearly similar osmolality. Erythrocyte aggregation at constant hematocrit (HT = 40%) was determined by the analysis of the light backscattered by blood suspension during the aggregation process. As compared to control samples, non ionic CM induced a weak decrease in erythrocyte aggregation, when the ionic molecule caused a marked increase in the aggregation, which was related to CM concentration. A different interaction of ionic and non ionic CM with erythrocyte membranes has been shown by fluorescence studies. After addition of CM, it was noted a fluorescence quenching of lipophilic probes (TMA-DPH and DPH) embedded in erythrocyte membranes. This quenching probably due to benzene ring and iodine atoms of contrast media markedly varied according to the used fluorescent probe and the CM. In the presence of ionic CM, the fluorescence quenching is more important than that induced by non ionic CM. Thus, besides osmolality and viscosity of CM which play a role in erythrocyte aggregation, some intrinsic properties of CM such as the ionic or non ionic nature could influence erythrocyte membrane-contrast medium interactions and consequently erythrocyte aggregation.
Diphenylhexatriene↗